Turning PET Plastic Into Paracetamol With This One Bacterial Trick

Over the course of evolution microorganisms have evolved pathways to break down many materials. The challenge with the many materials that we humans have created over just the past decades is that we cannot wait for evolution to catch up, ergo we have to develop such pathways ourselves. One such example is demonstrated by [Nick W. Johnson] et al. with a recent study in Nature Chemistry that explicitly targets PET plastic, which is very commonly used in plastic bottles.

The researchers modified regular E. coli bacteria to use PET plastic as an input via Lossen rearrangement, which converts hydroxamate esters to isocyanates, with at the end of the pathway para-aminobenzoate (PABA)  resulting, which using biosynthesis created paracetamol, the active ingredient in Tylenol. This new pathway is also completely harmless to the bacterium, which is always a potential pitfall with this kind of biological pathway engineering.

In addition to this offering a potential way to convert PET bottles into paracetamol, the researchers note that their findings could be very beneficial to studies targeting other ‘waste’ products from biological pathways.

Thanks to [DjBiohazard] for the tip.

PetBot: Turn PET Bottles Into Filament

Recycling plastic into filament normally involves chopping it into tiny pieces and pushing it through a screw extruder. [JRT3D] is taking a different approach with PetBot, which cuts PET bottles into tape and then turns it into filament. See the videos after the break.

Cutting the tape and extrusion happens in two completely separated processes on the same machine. A PET bottle is prepared by cutting off the bottom, and the open rim is pushed between a pair of bearings, where a cutter slices the bottle into one long strip, as a driven spool rolls it up. The spool of tape is then moved to the second stage of the machine, which pulls the tape through a hot end very similar to that on a 3D printer. While most conventional extruders push the plastic through a nozzle with a screw, the PetBot only heats up the tape to slightly above its glass transition temperature, which allows the driven spool to slowly pull it through the nozzle without breaking. A fan cools the filament just before it goes onto the spool. The same stepper motor is used for both stages of the process.

We like the simplicity of this machine compared to a conventional screw extruder, but it’s not without trade-offs. Firstly is the limitation of the filament length by the material in a single bottle. Getting longer lengths would involve fusing the tape after cutting, or the filament after extrusion, which is not as simple as it might seem. The process would likely be limited to large soda bottle with smooth exterior surfaces to allow the thickness and width of the tape to be as consistent as possible. We are curious to see the consistency of the filaments shape and diameter, and how sensitive it is to variations in the thickness and width of the tape. That being said, as long as you understand the limitations of the machine, we do not doubt that it can be useful. Continue reading “PetBot: Turn PET Bottles Into Filament”